Kettu Kalyanam, also known as Thali Kettu was the name of an elaborate marriage ceremony of the Nair communities of the southern Indian state of Kerala. The customs varied from region to region and caste to caste. Sambandham may take place only if the bride had already had this elaborate ritual marriage known as Kettu Kalyanam. This practice was not performed in North Malabar.
Among the Nair of Central Kerala, every ten or twelve years each lineage held a grand ceremony at its oldest ancestral house, at which time all immature girls of the lineage of one generation were ritually married by men of "enangar" groups. (linked neighborhood kinship groups not of the same family group as the brides) This ceremony, called tālikettukalyānam ("tāli-tying ceremony") had to be performed for each girl before puberty, on pain of her excommunication from her caste. (Gough, 1955)
At the ceremony, each bridegroom, in the company of representatives of every household in the neighborhood, tied a gold ornament (tāli) round the neck of his bride. Each couple was then secluded in a room of the ancestral house for three days and nights. On the fourth day the bridegrooms departed; they had no further obligations, and did not need to visit them again.
After the tāli ritual, a girl was regarded as having attained the status of a mature woman, ready to bear children to perpetuate her lineage.She also was free to engage in sexual liaisons with one or more men of her caste(or of an appropriate higher caste.)
The tāli ceremony was a both a religious and legal ceremony between the lineage and enangu group, and thus can be seen as a form of mass marriage.
- Cathleen Gough, Matrilinear Kinship, 1961 University of California Press Ltd: Berkeley and Los Angeles, pp 328 - 329 Retrieved from https://books.google.com/books?id=lfdvTbfilYAC&printsec=copyright&source=gbs_pub_info_r#v=onepage&q&f=false